In order to improve safety of pedestrians, joggers, workers on roadways, etc., retroreflective markings have been attached to clothing. In one common embodiment, retroreflective appliques comprising a monolayer of retroreflective elements, e.g., transparent microspheres with hemispheric reflectors, partially embedded in a layer of binder material, with adhesive backings are bonded to articles of clothing.
Typically, the binder materials in such appliques comprise thermally or chemically cured compositions, e.g., phenolic cured resins, isocyanate cured polymers with active hydrogens such as two part urethanes, and aminoplast- or amine-cured hydroxy functional polymers. A problem with such appliques is that their retroreflective performance tends to diminish unacceptably when the garment to which they are bonded is washed. After a few washings, the retroreflective brightness of the applique may be reduced to a small fraction, e.g., 5 percent or less, of its original brightness. This decrease is due to loss of retroreflective elements from the surface of the applique and/or degradation of the retroreflective elements, e.g., corrosion of aluminum hemispheric reflectors, during washing.
The problem is particularly troublesome when the clothing is subjected to industrial laundering, where the conditions of laundering are often more severe than conventional home laundering. For instance, in an industrial laundry, the laundering conditions may include wash temperatures of 40.degree. to 90.degree. C. (105.degree. to 190.degree. F.) and pH of 10 to 12.5, whereas in contrast, typical conditions for home laundering may include temperatures of 4.degree. to 60.degree. C. (40.degree. to 140.degree. F.) and pH of less than 11. Also, home laundering equipment typically subjects the articles being cleaned to less rigorous handling and stress than does industrial laundry equipment.